There is known a display system in notification systems that transmit information about obstacles around vehicles to drivers, the displaying system reflecting an image-displaying light with a windshield to the driver's eyes to display a virtual image in front of the vehicle. The information is thereby transmitted to the driver.
Such a display system virtually displays a display image framing an obstacle that requires attention of the driver, if the obstacle is viewed through the windshield. The driver is thus permitted to understand a position of the obstacle (see Patent Literature 1).